Examination of Three-Dimensional (3-D) Effects on Sound Propagation through Mesoscale Features Using 3-D Coupled Mode Theory.

摘要

A study of the three dimensional (3-D) effects of mesoscale variability on underwater sound propagation is conducted by interfacing the Chiu-Ehret 3-D acoustic coupled mode (CM) model with a forecasted sound speed field generated by the Harvard open ocean model (HOOM) This research concentrates on the sensitivity of the acoustic wave field to source depth and location with respect to a core ring in the Gulf Stream system for a 50 Hz sound source. The inclusion of the exact 3-D physics in acoustics modeling requires substantial computer resources. For this reason, it is very desirable to determine when the simpler adiabatic or Nx2-D approximations may be used. To achieve this goal, exact 3-D acoustic coupled mode model calculations are compared to results from the adiabatic approximation and Nx2-D approximation in terms of transmission loss and phases and amplitudes of individual mode modulation envelopes. The results show that the accuracy of the adiabatic and Nx2-D approximations depend strongly on the radial and transverse sound speed gradients along the track and the acoustic quality considered. Underwater sound propagation modeling.